This image of the Pinwheel Galaxy (M101) combines images from four different telescopes. Red shows the cool dust in the galaxy, as revealed by infrared light. Yellow shows visible starlight. Cyan (blue) shows the hottest and youngest stars glowing brightly in ultraviolet light. And magenta (purple) shows incredibly hot matter emitting x-rays as it is being pulled into a black hole.

The Science of Space Art

This image of the Pinwheel Galaxy (M101) combines images from four different telescopes. Red shows the cool dust in the galaxy, as revealed by infrared light. Yellow shows visible starlight. Cyan (blue) shows the hottest and youngest stars glowing brightly in ultraviolet light. And magenta (purple) shows incredibly hot matter emitting x-rays as it is being pulled into a black hole.

You may have seen colorful, eye-popping space images in books or on NASA websites. There are beautiful spiral galaxies that shine in pinks and blues; glowing green and yellow clouds with great white-tipped columns; or the radiant leftovers of exploded stars that may look like an eye or a spider.

Many of these images were made by capturing light that is not even visible to humans. We see only a very tiny portion of the huge range of light that is all around us. There are far more “colors” we cannot see than colors we can see.

Some telescopes can sense infra-red light. The Spitzer Space Telescope is one of these. Infrared light has too little energy for your eyes to notice it. But very cool material, like space gas, glows in infrared light. Another kind of telescope senses ultraviolet light. This kind of light has too much energy for your eyes to respond. Hot objects like newly forming stars glow in ultraviolet light.

So, if these telescopes see “invisible” light, how can our eyes even see the images they make? Where do those beautiful pinks and blues and yellows come from? Do scientists “colorize” them or give them fake colors?

No! If someone speaks to you in a language you do not understand, you need someone else to translate the message into your language. In the same way, you need to have the colors of the space images translated into something you can see.

Scientists process these “invisible” space images so we can see them. The new colors also help the scientists tease out all sorts of information the light can reveal. For example, a good job of translating colors can reveal the temperature differences between stars, dust, and gas in the images. The colors can also be made to show fine details that would otherwise be hard to see.